For centuries, it was known that people who survived smallpox became immune to it. For that reason, nearly every culture tried to induce immunity in healthy individuals. The Chinese used tubes to insert powdered smallpox scabs into their nostrils. In Turkey, pus from lesions was scratched into the skin.
Climate graph San Francisco. The driest month is July. There is 1 mm of precipitation in July. Most precipitation falls in January, with an average of 115 mm. Temperature graph San Francisco. With an average of 17.6 Â°C, September is the warmest month. In January, the average temperature is 10.4 Â°C. It is the lowest average temperature of the whole year. San Francisco Climate table // historical Weather data
The summary climate graph for San Francisco, CA shows a selection of temperature, rainfall and snow minimum, mean and maximum measures over the course of a year. Click on each of the measures in the key to toggle them on and off.